add graceful process termination on windows (#82)

proxy/process_stop_windows.go

@@ -0,0 +1,14 @@
+//go:build windows
+
+package proxy
+
+import (
+	"fmt"
+	"os/exec"
+)
+
+func (p *Process) terminateProcess() error {
+	pid := fmt.Sprintf("%d", p.cmd.Process.Pid)
+	cmd := exec.Command("taskkill", "/f", "/t", "/pid", pid)
+	return cmd.Run()
+}